The XML-RPC is a system that allows login and remote updates to WordPress from other applications.


If you need XML-RPC functionality (e.g. if you use the WordPress iPhone/Android App), and you want to by-pass login protection rules, simply enable "XML-RPC Compatibility" option. 


To achive this, select General tab from Shield main menu => Plugin Defaults => and click the slider to enable XML-RPC Compatibility option: